Acute and chronic effects of an extreme wood smoke exposure event in a rural community Abstract The recent wildfire season in the western United States resulted in many communities being exposed to high particulate matter (PM) levels. Among the more heavily impacted communities, Seeley Lake, MT experienced average daily levels of >200 g/m3 PM2.5 from July 31 to September 18, 2017, including several sustained exceedances of 1 mg/m3 PM2.5. This event presents as both a concern to the impacted communities and an opportunity to gain new information that could be used to inform risk guidance and prevention strategies for extreme woodsmoke exposures. Our team conducted a rapid response screening activity shortly following the wildland fire event in Seeley Lake to capture physiological and mental health measures as well as community response to public health messaging. The proposed follow-up study is particularly important as the differential health impacts of woodsmoke PM2.5 and fossil fuel PM2.5 are not well known. Furthermore, based on the increasing number of fires in the western US over the past couple of decades, there is concern that the number of individuals exposed to high levels of woodsmoke PM2.5 for more extended periods of time will continue to increase. Therefore, the purpose of this Time Sensitive Research Opportunities in Environmental Health Sciences R21 application is to fill this gap of knowledge and address the impacts of the recent fire season by obtaining clinical outcomes, bio-specimens and questionnaire data to identify the acute impacts on human health in Seeley Lake as well as a comparison community. We will also develop a strategy for long-term follow- up studies to determine chronic health impacts from these exposures. We propose to test the central hypothesis that sustained (> 1 month) exposure to hazardous levels of smoke from wildfires results in long-term adverse health effects. We will use the following two aims to test this hypothesis: Aim 1: Exposure to high levels of wood smoke-derived PM2.5 will result in sustained (greater than 6 months) adverse cardiovascular and respiratory health effects. Aim 2: Exposure to high levels of wood smoke-derived will result in sustained (greater than 6 months) adverse mental health effects. This proposal is based on the expertise in the Center for Environmental Health Sciences (CEHS) and the School of Pharmacy to study wood smoke health effects. We have: 1) expertise in wood smoke studies, 2) a unique wood smoke exposure research core, 3) a mobile IPHARM (ImProving Health Among Rural Montanans) resource that has extensive experience in working with rural Montana communities to conduct multidisciplinary health care screenings, 4) the extensive core facilities at CEHS to conduct analyses of small bio-specimens, and 5) we hosted an international conference on wood smoke health effects funded by the CDC 1. Less understood is the extent and duration of health effects following a sustained, high-level exposure, including long-term outcomes.